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1 ------------------------------------------------------------------------------
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2 -- --
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3 -- GNAT RUN-TIME LIBRARY (GNARL) COMPONENTS --
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4 -- --
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5 -- SYSTEM.TASKING.PROTECTED_OBJECTS.OPERATIONS --
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6 -- --
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7 -- B o d y --
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8 -- --
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131
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9 -- Copyright (C) 1998-2018, Free Software Foundation, Inc. --
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111
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10 -- --
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11 -- GNARL is free software; you can redistribute it and/or modify it under --
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12 -- terms of the GNU General Public License as published by the Free Soft- --
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13 -- ware Foundation; either version 3, or (at your option) any later ver- --
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14 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
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15 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
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16 -- or FITNESS FOR A PARTICULAR PURPOSE. --
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17 -- --
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18 -- As a special exception under Section 7 of GPL version 3, you are granted --
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19 -- additional permissions described in the GCC Runtime Library Exception, --
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20 -- version 3.1, as published by the Free Software Foundation. --
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21 -- --
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22 -- You should have received a copy of the GNU General Public License and --
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23 -- a copy of the GCC Runtime Library Exception along with this program; --
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24 -- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
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25 -- <http://www.gnu.org/licenses/>. --
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26 -- --
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27 -- GNARL was developed by the GNARL team at Florida State University. --
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28 -- Extensive contributions were provided by Ada Core Technologies, Inc. --
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29 -- --
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30 ------------------------------------------------------------------------------
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31
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32 -- This package contains all extended primitives related to Protected_Objects
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33 -- with entries.
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34
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35 -- The handling of protected objects with no entries is done in
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36 -- System.Tasking.Protected_Objects, the simple routines for protected
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37 -- objects with entries in System.Tasking.Protected_Objects.Entries.
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38
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39 -- The split between Entries and Operations is needed to break circular
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40 -- dependencies inside the run time.
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41
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42 -- This package contains all primitives related to Protected_Objects.
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43 -- Note: the compiler generates direct calls to this interface, via Rtsfind.
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44
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45 with System.Task_Primitives.Operations;
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46 with System.Tasking.Entry_Calls;
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47 with System.Tasking.Queuing;
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48 with System.Tasking.Rendezvous;
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49 with System.Tasking.Utilities;
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50 with System.Tasking.Debug;
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51 with System.Parameters;
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52 with System.Restrictions;
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53
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54 with System.Tasking.Initialization;
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55 pragma Elaborate_All (System.Tasking.Initialization);
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56 -- Insures that tasking is initialized if any protected objects are created
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57
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58 package body System.Tasking.Protected_Objects.Operations is
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59
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60 package STPO renames System.Task_Primitives.Operations;
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61
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62 use Parameters;
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63 use Ada.Exceptions;
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64 use Entries;
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65
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66 use System.Restrictions;
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67 use System.Restrictions.Rident;
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68
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69 -----------------------
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70 -- Local Subprograms --
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71 -----------------------
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72
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73 procedure Update_For_Queue_To_PO
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74 (Entry_Call : Entry_Call_Link;
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75 With_Abort : Boolean);
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76 pragma Inline (Update_For_Queue_To_PO);
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77 -- Update the state of an existing entry call to reflect the fact that it
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78 -- is being enqueued, based on whether the current queuing action is with
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79 -- or without abort. Call this only while holding the PO's lock. It returns
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80 -- with the PO's lock still held.
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81
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82 procedure Requeue_Call
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83 (Self_Id : Task_Id;
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84 Object : Protection_Entries_Access;
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85 Entry_Call : Entry_Call_Link);
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86 -- Handle requeue of Entry_Call.
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87 -- In particular, queue the call if needed, or service it immediately
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88 -- if possible.
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89
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90 ---------------------------------
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91 -- Cancel_Protected_Entry_Call --
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92 ---------------------------------
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93
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94 -- Compiler interface only (do not call from within the RTS)
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95
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96 -- This should have analogous effect to Cancel_Task_Entry_Call, setting
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97 -- the value of Block.Cancelled instead of returning the parameter value
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98 -- Cancelled.
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99
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100 -- The effect should be idempotent, since the call may already have been
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101 -- dequeued.
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102
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103 -- Source code:
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104
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105 -- select r.e;
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106 -- ...A...
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107 -- then abort
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108 -- ...B...
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109 -- end select;
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110
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111 -- Expanded code:
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112
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113 -- declare
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114 -- X : protected_entry_index := 1;
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115 -- B80b : communication_block;
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116 -- communication_blockIP (B80b);
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117
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118 -- begin
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119 -- begin
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120 -- A79b : label
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121 -- A79b : declare
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122 -- procedure _clean is
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123 -- begin
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124 -- if enqueued (B80b) then
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125 -- cancel_protected_entry_call (B80b);
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126 -- end if;
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127 -- return;
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128 -- end _clean;
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129
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130 -- begin
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131 -- protected_entry_call (rTV!(r)._object'unchecked_access, X,
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132 -- null_address, asynchronous_call, B80b, objectF => 0);
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133 -- if enqueued (B80b) then
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134 -- ...B...
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135 -- end if;
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136 -- at end
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137 -- _clean;
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138 -- end A79b;
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139
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140 -- exception
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141 -- when _abort_signal =>
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142 -- abort_undefer.all;
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143 -- null;
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144 -- end;
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145
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146 -- if not cancelled (B80b) then
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147 -- x := ...A...
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148 -- end if;
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149 -- end;
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150
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151 -- If the entry call completes after we get into the abortable part,
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152 -- Abort_Signal should be raised and ATC will take us to the at-end
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153 -- handler, which will call _clean.
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154
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155 -- If the entry call returns with the call already completed, we can skip
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156 -- this, and use the "if enqueued()" to go past the at-end handler, but we
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157 -- will still call _clean.
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158
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159 -- If the abortable part completes before the entry call is Done, it will
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160 -- call _clean.
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161
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162 -- If the entry call or the abortable part raises an exception,
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163 -- we will still call _clean, but the value of Cancelled should not matter.
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164
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165 -- Whoever calls _clean first gets to decide whether the call
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166 -- has been "cancelled".
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167
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168 -- Enqueued should be true if there is any chance that the call is still on
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169 -- a queue. It seems to be safe to make it True if the call was Onqueue at
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170 -- some point before return from Protected_Entry_Call.
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171
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172 -- Cancelled should be true iff the abortable part completed
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173 -- and succeeded in cancelling the entry call before it completed.
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174
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175 -- ?????
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176 -- The need for Enqueued is less obvious. The "if enqueued ()" tests are
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177 -- not necessary, since Cancel_Protected_Entry_Call/Protected_Entry_Call
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178 -- must do the same test internally, with locking. The one that makes
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179 -- cancellation conditional may be a useful heuristic since at least 1/2
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180 -- the time the call should be off-queue by that point. The other one seems
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181 -- totally useless, since Protected_Entry_Call must do the same check and
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182 -- then possibly wait for the call to be abortable, internally.
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183
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184 -- We can check Call.State here without locking the caller's mutex,
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185 -- since the call must be over after returning from Wait_For_Completion.
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186 -- No other task can access the call record at this point.
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187
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188 procedure Cancel_Protected_Entry_Call
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189 (Block : in out Communication_Block) is
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190 begin
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191 Entry_Calls.Try_To_Cancel_Entry_Call (Block.Cancelled);
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192 end Cancel_Protected_Entry_Call;
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193
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194 ---------------
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195 -- Cancelled --
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196 ---------------
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197
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198 function Cancelled (Block : Communication_Block) return Boolean is
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199 begin
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200 return Block.Cancelled;
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201 end Cancelled;
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202
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203 -------------------------
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204 -- Complete_Entry_Body --
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205 -------------------------
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206
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207 procedure Complete_Entry_Body (Object : Protection_Entries_Access) is
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208 begin
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209 Exceptional_Complete_Entry_Body (Object, Ada.Exceptions.Null_Id);
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210 end Complete_Entry_Body;
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211
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212 --------------
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213 -- Enqueued --
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214 --------------
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215
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216 function Enqueued (Block : Communication_Block) return Boolean is
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217 begin
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218 return Block.Enqueued;
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219 end Enqueued;
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220
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221 -------------------------------------
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222 -- Exceptional_Complete_Entry_Body --
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223 -------------------------------------
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224
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225 procedure Exceptional_Complete_Entry_Body
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226 (Object : Protection_Entries_Access;
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227 Ex : Ada.Exceptions.Exception_Id)
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228 is
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229 procedure Transfer_Occurrence
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230 (Target : Ada.Exceptions.Exception_Occurrence_Access;
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231 Source : Ada.Exceptions.Exception_Occurrence);
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232 pragma Import (C, Transfer_Occurrence, "__gnat_transfer_occurrence");
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233
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234 Entry_Call : constant Entry_Call_Link := Object.Call_In_Progress;
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235 Self_Id : Task_Id;
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236
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237 begin
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238 pragma Debug
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239 (Debug.Trace (STPO.Self, "Exceptional_Complete_Entry_Body", 'P'));
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240
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241 -- We must have abort deferred, since we are inside a protected
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242 -- operation.
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243
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244 if Entry_Call /= null then
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245
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246 -- The call was not requeued
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247
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248 Entry_Call.Exception_To_Raise := Ex;
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249
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250 if Ex /= Ada.Exceptions.Null_Id then
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251
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252 -- An exception was raised and abort was deferred, so adjust
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253 -- before propagating, otherwise the task will stay with deferral
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254 -- enabled for its remaining life.
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255
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256 Self_Id := STPO.Self;
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257
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258 if not ZCX_By_Default then
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259 Initialization.Undefer_Abort_Nestable (Self_Id);
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260 end if;
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261
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262 Transfer_Occurrence
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263 (Entry_Call.Self.Common.Compiler_Data.Current_Excep'Access,
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264 Self_Id.Common.Compiler_Data.Current_Excep);
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265 end if;
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266
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267 -- Wakeup_Entry_Caller will be called from PO_Do_Or_Queue or
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268 -- PO_Service_Entries on return.
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269
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270 end if;
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271 end Exceptional_Complete_Entry_Body;
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272
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273 --------------------
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274 -- PO_Do_Or_Queue --
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275 --------------------
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276
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277 procedure PO_Do_Or_Queue
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278 (Self_ID : Task_Id;
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279 Object : Protection_Entries_Access;
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280 Entry_Call : Entry_Call_Link)
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281 is
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282 E : constant Protected_Entry_Index :=
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283 Protected_Entry_Index (Entry_Call.E);
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284 Index : constant Protected_Entry_Index :=
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285 Object.Find_Body_Index (Object.Compiler_Info, E);
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286 Barrier_Value : Boolean;
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287 Queue_Length : Natural;
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288 begin
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289 -- When the Action procedure for an entry body returns, it is either
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290 -- completed (having called [Exceptional_]Complete_Entry_Body) or it
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291 -- is queued, having executed a requeue statement.
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292
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293 Barrier_Value :=
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294 Object.Entry_Bodies (Index).Barrier (Object.Compiler_Info, E);
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295
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296 if Barrier_Value then
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297
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298 -- Not abortable while service is in progress
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299
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300 if Entry_Call.State = Now_Abortable then
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301 Entry_Call.State := Was_Abortable;
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302 end if;
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303
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304 Object.Call_In_Progress := Entry_Call;
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305
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306 pragma Debug
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307 (Debug.Trace (Self_ID, "PODOQ: start entry body", 'P'));
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308 Object.Entry_Bodies (Index).Action (
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309 Object.Compiler_Info, Entry_Call.Uninterpreted_Data, E);
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310
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311 if Object.Call_In_Progress /= null then
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312
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313 -- Body of current entry served call to completion
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314
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315 Object.Call_In_Progress := null;
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316
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317 if Single_Lock then
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318 STPO.Lock_RTS;
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319 end if;
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320
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321 STPO.Write_Lock (Entry_Call.Self);
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322 Initialization.Wakeup_Entry_Caller (Self_ID, Entry_Call, Done);
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323 STPO.Unlock (Entry_Call.Self);
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324
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325 if Single_Lock then
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326 STPO.Unlock_RTS;
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327 end if;
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328
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329 else
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330 Requeue_Call (Self_ID, Object, Entry_Call);
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331 end if;
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332
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333 elsif Entry_Call.Mode /= Conditional_Call
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334 or else not Entry_Call.With_Abort
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335 then
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336 if Run_Time_Restrictions.Set (Max_Entry_Queue_Length)
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337 or else Object.Entry_Queue_Maxes /= null
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338 then
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339 -- Need to check the queue length. Computing the length is an
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340 -- unusual case and is slow (need to walk the queue).
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341
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342 Queue_Length := Queuing.Count_Waiting (Object.Entry_Queues (E));
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343
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344 if (Run_Time_Restrictions.Set (Max_Entry_Queue_Length)
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345 and then Queue_Length >=
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346 Run_Time_Restrictions.Value (Max_Entry_Queue_Length))
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347 or else
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348 (Object.Entry_Queue_Maxes /= null
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349 and then Object.Entry_Queue_Maxes (Index) /= 0
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350 and then Queue_Length >= Object.Entry_Queue_Maxes (Index))
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351 then
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352 -- This violates the Max_Entry_Queue_Length restriction or the
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353 -- Max_Queue_Length bound, raise Program_Error.
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354
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355 Entry_Call.Exception_To_Raise := Program_Error'Identity;
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356
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357 if Single_Lock then
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358 STPO.Lock_RTS;
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359 end if;
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360
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361 STPO.Write_Lock (Entry_Call.Self);
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362 Initialization.Wakeup_Entry_Caller (Self_ID, Entry_Call, Done);
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363 STPO.Unlock (Entry_Call.Self);
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364
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365 if Single_Lock then
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366 STPO.Unlock_RTS;
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367 end if;
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368
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369 return;
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370 end if;
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371 end if;
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372
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373 -- Do the work: queue the call
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374
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375 Queuing.Enqueue (Object.Entry_Queues (E), Entry_Call);
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376 Update_For_Queue_To_PO (Entry_Call, Entry_Call.With_Abort);
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377
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378 return;
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379 else
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380 -- Conditional_Call and With_Abort
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381
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382 if Single_Lock then
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383 STPO.Lock_RTS;
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384 end if;
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385
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386 STPO.Write_Lock (Entry_Call.Self);
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387 pragma Assert (Entry_Call.State /= Not_Yet_Abortable);
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388 Initialization.Wakeup_Entry_Caller (Self_ID, Entry_Call, Cancelled);
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389 STPO.Unlock (Entry_Call.Self);
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390
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391 if Single_Lock then
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392 STPO.Unlock_RTS;
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393 end if;
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394 end if;
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395
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396 exception
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397 when others =>
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398 Queuing.Broadcast_Program_Error (Self_ID, Object, Entry_Call);
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399 end PO_Do_Or_Queue;
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400
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401 ------------------------
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402 -- PO_Service_Entries --
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403 ------------------------
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404
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405 procedure PO_Service_Entries
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406 (Self_ID : Task_Id;
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407 Object : Entries.Protection_Entries_Access;
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408 Unlock_Object : Boolean := True)
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409 is
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410 E : Protected_Entry_Index;
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411 Caller : Task_Id;
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412 Entry_Call : Entry_Call_Link;
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413
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414 begin
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415 loop
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416 Queuing.Select_Protected_Entry_Call (Self_ID, Object, Entry_Call);
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417
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418 exit when Entry_Call = null;
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419
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420 E := Protected_Entry_Index (Entry_Call.E);
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421
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422 -- Not abortable while service is in progress
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423
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424 if Entry_Call.State = Now_Abortable then
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425 Entry_Call.State := Was_Abortable;
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426 end if;
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427
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428 Object.Call_In_Progress := Entry_Call;
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429
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430 begin
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431 pragma Debug
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432 (Debug.Trace (Self_ID, "POSE: start entry body", 'P'));
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433
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434 Object.Entry_Bodies
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435 (Object.Find_Body_Index (Object.Compiler_Info, E)).Action
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436 (Object.Compiler_Info, Entry_Call.Uninterpreted_Data, E);
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437
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438 exception
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439 when others =>
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440 Queuing.Broadcast_Program_Error
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441 (Self_ID, Object, Entry_Call);
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442 end;
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443
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444 if Object.Call_In_Progress = null then
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445 Requeue_Call (Self_ID, Object, Entry_Call);
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446 exit when Entry_Call.State = Cancelled;
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447
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448 else
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449 Object.Call_In_Progress := null;
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450 Caller := Entry_Call.Self;
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451
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452 if Single_Lock then
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453 STPO.Lock_RTS;
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454 end if;
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455
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456 STPO.Write_Lock (Caller);
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457 Initialization.Wakeup_Entry_Caller (Self_ID, Entry_Call, Done);
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458 STPO.Unlock (Caller);
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459
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460 if Single_Lock then
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461 STPO.Unlock_RTS;
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462 end if;
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463 end if;
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464 end loop;
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465
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466 if Unlock_Object then
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467 Unlock_Entries (Object);
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468 end if;
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469 end PO_Service_Entries;
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470
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471 ---------------------
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472 -- Protected_Count --
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473 ---------------------
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474
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475 function Protected_Count
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476 (Object : Protection_Entries'Class;
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477 E : Protected_Entry_Index) return Natural
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478 is
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479 begin
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480 return Queuing.Count_Waiting (Object.Entry_Queues (E));
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481 end Protected_Count;
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482
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483 --------------------------
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484 -- Protected_Entry_Call --
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485 --------------------------
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486
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487 -- Compiler interface only (do not call from within the RTS)
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488
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489 -- select r.e;
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490 -- ...A...
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491 -- else
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492 -- ...B...
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493 -- end select;
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494
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495 -- declare
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496 -- X : protected_entry_index := 1;
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497 -- B85b : communication_block;
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498 -- communication_blockIP (B85b);
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499
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500 -- begin
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501 -- protected_entry_call (rTV!(r)._object'unchecked_access, X,
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502 -- null_address, conditional_call, B85b, objectF => 0);
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503
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504 -- if cancelled (B85b) then
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505 -- ...B...
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506 -- else
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507 -- ...A...
|
|
508 -- end if;
|
|
509 -- end;
|
|
510
|
|
511 -- See also Cancel_Protected_Entry_Call for code expansion of asynchronous
|
|
512 -- entry call.
|
|
513
|
|
514 -- The initial part of this procedure does not need to lock the calling
|
|
515 -- task's ATCB, up to the point where the call record first may be queued
|
|
516 -- (PO_Do_Or_Queue), since before that no other task will have access to
|
|
517 -- the record.
|
|
518
|
|
519 -- If this is a call made inside of an abort deferred region, the call
|
|
520 -- should be never abortable.
|
|
521
|
|
522 -- If the call was not queued abortably, we need to wait until it is before
|
|
523 -- proceeding with the abortable part.
|
|
524
|
|
525 -- There are some heuristics here, just to save time for frequently
|
|
526 -- occurring cases. For example, we check Initially_Abortable to try to
|
|
527 -- avoid calling the procedure Wait_Until_Abortable, since the normal case
|
|
528 -- for async. entry calls is to be queued abortably.
|
|
529
|
|
530 -- Another heuristic uses the Block.Enqueued to try to avoid calling
|
|
531 -- Cancel_Protected_Entry_Call if the call can be served immediately.
|
|
532
|
|
533 procedure Protected_Entry_Call
|
|
534 (Object : Protection_Entries_Access;
|
|
535 E : Protected_Entry_Index;
|
|
536 Uninterpreted_Data : System.Address;
|
|
537 Mode : Call_Modes;
|
|
538 Block : out Communication_Block)
|
|
539 is
|
|
540 Self_ID : constant Task_Id := STPO.Self;
|
|
541 Entry_Call : Entry_Call_Link;
|
|
542 Initially_Abortable : Boolean;
|
|
543 Ceiling_Violation : Boolean;
|
|
544
|
|
545 begin
|
|
546 pragma Debug
|
|
547 (Debug.Trace (Self_ID, "Protected_Entry_Call", 'P'));
|
|
548
|
|
549 if Self_ID.ATC_Nesting_Level = ATC_Level'Last then
|
|
550 raise Storage_Error with "not enough ATC nesting levels";
|
|
551 end if;
|
|
552
|
|
553 -- If pragma Detect_Blocking is active then Program_Error must be
|
|
554 -- raised if this potentially blocking operation is called from a
|
|
555 -- protected action.
|
|
556
|
|
557 if Detect_Blocking
|
|
558 and then Self_ID.Common.Protected_Action_Nesting > 0
|
|
559 then
|
|
560 raise Program_Error with "potentially blocking operation";
|
|
561 end if;
|
|
562
|
|
563 -- Self_ID.Deferral_Level should be 0, except when called from Finalize,
|
|
564 -- where abort is already deferred.
|
|
565
|
|
566 Initialization.Defer_Abort_Nestable (Self_ID);
|
|
567 Lock_Entries_With_Status (Object, Ceiling_Violation);
|
|
568
|
|
569 if Ceiling_Violation then
|
|
570
|
|
571 -- Failed ceiling check
|
|
572
|
|
573 Initialization.Undefer_Abort_Nestable (Self_ID);
|
|
574 raise Program_Error;
|
|
575 end if;
|
|
576
|
|
577 Block.Self := Self_ID;
|
|
578 Self_ID.ATC_Nesting_Level := Self_ID.ATC_Nesting_Level + 1;
|
|
579 pragma Debug
|
|
580 (Debug.Trace (Self_ID, "PEC: entered ATC level: " &
|
|
581 ATC_Level'Image (Self_ID.ATC_Nesting_Level), 'A'));
|
|
582 Entry_Call :=
|
|
583 Self_ID.Entry_Calls (Self_ID.ATC_Nesting_Level)'Access;
|
|
584 Entry_Call.Next := null;
|
|
585 Entry_Call.Mode := Mode;
|
|
586 Entry_Call.Cancellation_Attempted := False;
|
|
587
|
|
588 Entry_Call.State :=
|
|
589 (if Self_ID.Deferral_Level > 1
|
|
590 then Never_Abortable else Now_Abortable);
|
|
591
|
|
592 Entry_Call.E := Entry_Index (E);
|
|
593 Entry_Call.Prio := STPO.Get_Priority (Self_ID);
|
|
594 Entry_Call.Uninterpreted_Data := Uninterpreted_Data;
|
|
595 Entry_Call.Called_PO := To_Address (Object);
|
|
596 Entry_Call.Called_Task := null;
|
|
597 Entry_Call.Exception_To_Raise := Ada.Exceptions.Null_Id;
|
|
598 Entry_Call.With_Abort := True;
|
|
599
|
|
600 PO_Do_Or_Queue (Self_ID, Object, Entry_Call);
|
|
601 Initially_Abortable := Entry_Call.State = Now_Abortable;
|
|
602 PO_Service_Entries (Self_ID, Object);
|
|
603
|
|
604 -- Try to prevent waiting later (in Try_To_Cancel_Protected_Entry_Call)
|
|
605 -- for completed or cancelled calls. (This is a heuristic, only.)
|
|
606
|
|
607 if Entry_Call.State >= Done then
|
|
608
|
|
609 -- Once State >= Done it will not change any more
|
|
610
|
|
611 if Single_Lock then
|
|
612 STPO.Lock_RTS;
|
|
613 end if;
|
|
614
|
|
615 STPO.Write_Lock (Self_ID);
|
|
616 Utilities.Exit_One_ATC_Level (Self_ID);
|
|
617 STPO.Unlock (Self_ID);
|
|
618
|
|
619 if Single_Lock then
|
|
620 STPO.Unlock_RTS;
|
|
621 end if;
|
|
622
|
|
623 Block.Enqueued := False;
|
|
624 Block.Cancelled := Entry_Call.State = Cancelled;
|
|
625 Initialization.Undefer_Abort_Nestable (Self_ID);
|
|
626 Entry_Calls.Check_Exception (Self_ID, Entry_Call);
|
|
627 return;
|
|
628
|
|
629 else
|
|
630 -- In this case we cannot conclude anything, since State can change
|
|
631 -- concurrently.
|
|
632
|
|
633 null;
|
|
634 end if;
|
|
635
|
|
636 -- Now for the general case
|
|
637
|
|
638 if Mode = Asynchronous_Call then
|
|
639
|
|
640 -- Try to avoid an expensive call
|
|
641
|
|
642 if not Initially_Abortable then
|
|
643 if Single_Lock then
|
|
644 STPO.Lock_RTS;
|
|
645 Entry_Calls.Wait_Until_Abortable (Self_ID, Entry_Call);
|
|
646 STPO.Unlock_RTS;
|
|
647 else
|
|
648 Entry_Calls.Wait_Until_Abortable (Self_ID, Entry_Call);
|
|
649 end if;
|
|
650 end if;
|
|
651
|
|
652 else
|
|
653 case Mode is
|
|
654 when Conditional_Call
|
|
655 | Simple_Call
|
|
656 =>
|
|
657 if Single_Lock then
|
|
658 STPO.Lock_RTS;
|
|
659 Entry_Calls.Wait_For_Completion (Entry_Call);
|
|
660 STPO.Unlock_RTS;
|
|
661
|
|
662 else
|
|
663 STPO.Write_Lock (Self_ID);
|
|
664 Entry_Calls.Wait_For_Completion (Entry_Call);
|
|
665 STPO.Unlock (Self_ID);
|
|
666 end if;
|
|
667
|
|
668 Block.Cancelled := Entry_Call.State = Cancelled;
|
|
669
|
|
670 when Asynchronous_Call
|
|
671 | Timed_Call
|
|
672 =>
|
|
673 pragma Assert (False);
|
|
674 null;
|
|
675 end case;
|
|
676 end if;
|
|
677
|
|
678 Initialization.Undefer_Abort_Nestable (Self_ID);
|
|
679 Entry_Calls.Check_Exception (Self_ID, Entry_Call);
|
|
680 end Protected_Entry_Call;
|
|
681
|
|
682 ------------------
|
|
683 -- Requeue_Call --
|
|
684 ------------------
|
|
685
|
|
686 procedure Requeue_Call
|
|
687 (Self_Id : Task_Id;
|
|
688 Object : Protection_Entries_Access;
|
|
689 Entry_Call : Entry_Call_Link)
|
|
690 is
|
|
691 New_Object : Protection_Entries_Access;
|
|
692 Ceiling_Violation : Boolean;
|
|
693 Result : Boolean;
|
|
694 E : Protected_Entry_Index;
|
|
695
|
|
696 begin
|
|
697 New_Object := To_Protection (Entry_Call.Called_PO);
|
|
698
|
|
699 if New_Object = null then
|
|
700
|
|
701 -- Call is to be requeued to a task entry
|
|
702
|
|
703 if Single_Lock then
|
|
704 STPO.Lock_RTS;
|
|
705 end if;
|
|
706
|
|
707 Result := Rendezvous.Task_Do_Or_Queue (Self_Id, Entry_Call);
|
|
708
|
|
709 if not Result then
|
|
710 Queuing.Broadcast_Program_Error
|
|
711 (Self_Id, Object, Entry_Call, RTS_Locked => True);
|
|
712 end if;
|
|
713
|
|
714 if Single_Lock then
|
|
715 STPO.Unlock_RTS;
|
|
716 end if;
|
|
717
|
|
718 else
|
|
719 -- Call should be requeued to a PO
|
|
720
|
|
721 if Object /= New_Object then
|
|
722
|
|
723 -- Requeue is to different PO
|
|
724
|
|
725 Lock_Entries_With_Status (New_Object, Ceiling_Violation);
|
|
726
|
|
727 if Ceiling_Violation then
|
|
728 Object.Call_In_Progress := null;
|
|
729 Queuing.Broadcast_Program_Error (Self_Id, Object, Entry_Call);
|
|
730
|
|
731 else
|
|
732 PO_Do_Or_Queue (Self_Id, New_Object, Entry_Call);
|
|
733 PO_Service_Entries (Self_Id, New_Object);
|
|
734 end if;
|
|
735
|
|
736 else
|
|
737 -- Requeue is to same protected object
|
|
738
|
|
739 -- ??? Try to compensate apparent failure of the scheduler on some
|
|
740 -- OS (e.g VxWorks) to give higher priority tasks a chance to run
|
|
741 -- (see CXD6002).
|
|
742
|
|
743 STPO.Yield (Do_Yield => False);
|
|
744
|
|
745 if Entry_Call.With_Abort
|
|
746 and then Entry_Call.Cancellation_Attempted
|
|
747 then
|
|
748 -- If this is a requeue with abort and someone tried to cancel
|
|
749 -- this call, cancel it at this point.
|
|
750
|
|
751 Entry_Call.State := Cancelled;
|
|
752 return;
|
|
753 end if;
|
|
754
|
|
755 if not Entry_Call.With_Abort
|
|
756 or else Entry_Call.Mode /= Conditional_Call
|
|
757 then
|
|
758 E := Protected_Entry_Index (Entry_Call.E);
|
|
759
|
|
760 if Run_Time_Restrictions.Set (Max_Entry_Queue_Length)
|
|
761 and then
|
|
762 Run_Time_Restrictions.Value (Max_Entry_Queue_Length) <=
|
|
763 Queuing.Count_Waiting (Object.Entry_Queues (E))
|
|
764 then
|
|
765 -- This violates the Max_Entry_Queue_Length restriction,
|
|
766 -- raise Program_Error.
|
|
767
|
|
768 Entry_Call.Exception_To_Raise := Program_Error'Identity;
|
|
769
|
|
770 if Single_Lock then
|
|
771 STPO.Lock_RTS;
|
|
772 end if;
|
|
773
|
|
774 STPO.Write_Lock (Entry_Call.Self);
|
|
775 Initialization.Wakeup_Entry_Caller
|
|
776 (Self_Id, Entry_Call, Done);
|
|
777 STPO.Unlock (Entry_Call.Self);
|
|
778
|
|
779 if Single_Lock then
|
|
780 STPO.Unlock_RTS;
|
|
781 end if;
|
|
782
|
|
783 else
|
|
784 Queuing.Enqueue
|
|
785 (New_Object.Entry_Queues (E), Entry_Call);
|
|
786 Update_For_Queue_To_PO (Entry_Call, Entry_Call.With_Abort);
|
|
787 end if;
|
|
788
|
|
789 else
|
|
790 PO_Do_Or_Queue (Self_Id, New_Object, Entry_Call);
|
|
791 end if;
|
|
792 end if;
|
|
793 end if;
|
|
794 end Requeue_Call;
|
|
795
|
|
796 ----------------------------
|
|
797 -- Protected_Entry_Caller --
|
|
798 ----------------------------
|
|
799
|
|
800 function Protected_Entry_Caller
|
|
801 (Object : Protection_Entries'Class) return Task_Id is
|
|
802 begin
|
|
803 return Object.Call_In_Progress.Self;
|
|
804 end Protected_Entry_Caller;
|
|
805
|
|
806 -----------------------------
|
|
807 -- Requeue_Protected_Entry --
|
|
808 -----------------------------
|
|
809
|
|
810 -- Compiler interface only (do not call from within the RTS)
|
|
811
|
|
812 -- entry e when b is
|
|
813 -- begin
|
|
814 -- b := false;
|
|
815 -- ...A...
|
|
816 -- requeue e2;
|
|
817 -- end e;
|
|
818
|
|
819 -- procedure rPT__E10b (O : address; P : address; E :
|
|
820 -- protected_entry_index) is
|
|
821 -- type rTVP is access rTV;
|
|
822 -- freeze rTVP []
|
|
823 -- _object : rTVP := rTVP!(O);
|
|
824 -- begin
|
|
825 -- declare
|
|
826 -- rR : protection renames _object._object;
|
|
827 -- vP : integer renames _object.v;
|
|
828 -- bP : boolean renames _object.b;
|
|
829 -- begin
|
|
830 -- b := false;
|
|
831 -- ...A...
|
|
832 -- requeue_protected_entry (rR'unchecked_access, rR'
|
|
833 -- unchecked_access, 2, false, objectF => 0, new_objectF =>
|
|
834 -- 0);
|
|
835 -- return;
|
|
836 -- end;
|
|
837 -- complete_entry_body (_object._object'unchecked_access, objectF =>
|
|
838 -- 0);
|
|
839 -- return;
|
|
840 -- exception
|
|
841 -- when others =>
|
|
842 -- abort_undefer.all;
|
|
843 -- exceptional_complete_entry_body (_object._object'
|
|
844 -- unchecked_access, current_exception, objectF => 0);
|
|
845 -- return;
|
|
846 -- end rPT__E10b;
|
|
847
|
|
848 procedure Requeue_Protected_Entry
|
|
849 (Object : Protection_Entries_Access;
|
|
850 New_Object : Protection_Entries_Access;
|
|
851 E : Protected_Entry_Index;
|
|
852 With_Abort : Boolean)
|
|
853 is
|
|
854 Entry_Call : constant Entry_Call_Link := Object.Call_In_Progress;
|
|
855
|
|
856 begin
|
|
857 pragma Debug
|
|
858 (Debug.Trace (STPO.Self, "Requeue_Protected_Entry", 'P'));
|
|
859 pragma Assert (STPO.Self.Deferral_Level > 0);
|
|
860
|
|
861 Entry_Call.E := Entry_Index (E);
|
|
862 Entry_Call.Called_PO := To_Address (New_Object);
|
|
863 Entry_Call.Called_Task := null;
|
|
864 Entry_Call.With_Abort := With_Abort;
|
|
865 Object.Call_In_Progress := null;
|
|
866 end Requeue_Protected_Entry;
|
|
867
|
|
868 -------------------------------------
|
|
869 -- Requeue_Task_To_Protected_Entry --
|
|
870 -------------------------------------
|
|
871
|
|
872 -- Compiler interface only (do not call from within the RTS)
|
|
873
|
|
874 -- accept e1 do
|
|
875 -- ...A...
|
|
876 -- requeue r.e2;
|
|
877 -- end e1;
|
|
878
|
|
879 -- A79b : address;
|
|
880 -- L78b : label
|
|
881
|
|
882 -- begin
|
|
883 -- accept_call (1, A79b);
|
|
884 -- ...A...
|
|
885 -- requeue_task_to_protected_entry (rTV!(r)._object'
|
|
886 -- unchecked_access, 2, false, new_objectF => 0);
|
|
887 -- goto L78b;
|
|
888 -- <<L78b>>
|
|
889 -- complete_rendezvous;
|
|
890
|
|
891 -- exception
|
|
892 -- when all others =>
|
|
893 -- exceptional_complete_rendezvous (get_gnat_exception);
|
|
894 -- end;
|
|
895
|
|
896 procedure Requeue_Task_To_Protected_Entry
|
|
897 (New_Object : Protection_Entries_Access;
|
|
898 E : Protected_Entry_Index;
|
|
899 With_Abort : Boolean)
|
|
900 is
|
|
901 Self_ID : constant Task_Id := STPO.Self;
|
|
902 Entry_Call : constant Entry_Call_Link := Self_ID.Common.Call;
|
|
903
|
|
904 begin
|
|
905 Initialization.Defer_Abort (Self_ID);
|
|
906
|
|
907 -- We do not need to lock Self_ID here since the call is not abortable
|
|
908 -- at this point, and therefore, the caller cannot cancel the call.
|
|
909
|
|
910 Entry_Call.Needs_Requeue := True;
|
|
911 Entry_Call.With_Abort := With_Abort;
|
|
912 Entry_Call.Called_PO := To_Address (New_Object);
|
|
913 Entry_Call.Called_Task := null;
|
|
914 Entry_Call.E := Entry_Index (E);
|
|
915 Initialization.Undefer_Abort (Self_ID);
|
|
916 end Requeue_Task_To_Protected_Entry;
|
|
917
|
|
918 ---------------------
|
|
919 -- Service_Entries --
|
|
920 ---------------------
|
|
921
|
|
922 procedure Service_Entries (Object : Protection_Entries_Access) is
|
|
923 Self_ID : constant Task_Id := STPO.Self;
|
|
924 begin
|
|
925 PO_Service_Entries (Self_ID, Object);
|
|
926 end Service_Entries;
|
|
927
|
|
928 --------------------------------
|
|
929 -- Timed_Protected_Entry_Call --
|
|
930 --------------------------------
|
|
931
|
|
932 -- Compiler interface only (do not call from within the RTS)
|
|
933
|
|
934 procedure Timed_Protected_Entry_Call
|
|
935 (Object : Protection_Entries_Access;
|
|
936 E : Protected_Entry_Index;
|
|
937 Uninterpreted_Data : System.Address;
|
|
938 Timeout : Duration;
|
|
939 Mode : Delay_Modes;
|
|
940 Entry_Call_Successful : out Boolean)
|
|
941 is
|
|
942 Self_Id : constant Task_Id := STPO.Self;
|
|
943 Entry_Call : Entry_Call_Link;
|
|
944 Ceiling_Violation : Boolean;
|
|
945
|
|
946 Yielded : Boolean;
|
|
947 pragma Unreferenced (Yielded);
|
|
948
|
|
949 begin
|
|
950 if Self_Id.ATC_Nesting_Level = ATC_Level'Last then
|
|
951 raise Storage_Error with "not enough ATC nesting levels";
|
|
952 end if;
|
|
953
|
|
954 -- If pragma Detect_Blocking is active then Program_Error must be
|
|
955 -- raised if this potentially blocking operation is called from a
|
|
956 -- protected action.
|
|
957
|
|
958 if Detect_Blocking
|
|
959 and then Self_Id.Common.Protected_Action_Nesting > 0
|
|
960 then
|
|
961 raise Program_Error with "potentially blocking operation";
|
|
962 end if;
|
|
963
|
|
964 Initialization.Defer_Abort_Nestable (Self_Id);
|
|
965 Lock_Entries_With_Status (Object, Ceiling_Violation);
|
|
966
|
|
967 if Ceiling_Violation then
|
|
968 Initialization.Undefer_Abort (Self_Id);
|
|
969 raise Program_Error;
|
|
970 end if;
|
|
971
|
|
972 Self_Id.ATC_Nesting_Level := Self_Id.ATC_Nesting_Level + 1;
|
|
973 pragma Debug
|
|
974 (Debug.Trace (Self_Id, "TPEC: exited to ATC level: " &
|
|
975 ATC_Level'Image (Self_Id.ATC_Nesting_Level), 'A'));
|
|
976 Entry_Call := Self_Id.Entry_Calls (Self_Id.ATC_Nesting_Level)'Access;
|
|
977 Entry_Call.Next := null;
|
|
978 Entry_Call.Mode := Timed_Call;
|
|
979 Entry_Call.Cancellation_Attempted := False;
|
|
980
|
|
981 Entry_Call.State :=
|
|
982 (if Self_Id.Deferral_Level > 1
|
|
983 then Never_Abortable
|
|
984 else Now_Abortable);
|
|
985
|
|
986 Entry_Call.E := Entry_Index (E);
|
|
987 Entry_Call.Prio := STPO.Get_Priority (Self_Id);
|
|
988 Entry_Call.Uninterpreted_Data := Uninterpreted_Data;
|
|
989 Entry_Call.Called_PO := To_Address (Object);
|
|
990 Entry_Call.Called_Task := null;
|
|
991 Entry_Call.Exception_To_Raise := Ada.Exceptions.Null_Id;
|
|
992 Entry_Call.With_Abort := True;
|
|
993
|
|
994 PO_Do_Or_Queue (Self_Id, Object, Entry_Call);
|
|
995 PO_Service_Entries (Self_Id, Object);
|
|
996
|
|
997 if Single_Lock then
|
|
998 STPO.Lock_RTS;
|
|
999 else
|
|
1000 STPO.Write_Lock (Self_Id);
|
|
1001 end if;
|
|
1002
|
|
1003 -- Try to avoid waiting for completed or cancelled calls
|
|
1004
|
|
1005 if Entry_Call.State >= Done then
|
|
1006 Utilities.Exit_One_ATC_Level (Self_Id);
|
|
1007
|
|
1008 if Single_Lock then
|
|
1009 STPO.Unlock_RTS;
|
|
1010 else
|
|
1011 STPO.Unlock (Self_Id);
|
|
1012 end if;
|
|
1013
|
|
1014 Entry_Call_Successful := Entry_Call.State = Done;
|
|
1015 Initialization.Undefer_Abort_Nestable (Self_Id);
|
|
1016 Entry_Calls.Check_Exception (Self_Id, Entry_Call);
|
|
1017 return;
|
|
1018 end if;
|
|
1019
|
|
1020 Entry_Calls.Wait_For_Completion_With_Timeout
|
|
1021 (Entry_Call, Timeout, Mode, Yielded);
|
|
1022
|
|
1023 if Single_Lock then
|
|
1024 STPO.Unlock_RTS;
|
|
1025 else
|
|
1026 STPO.Unlock (Self_Id);
|
|
1027 end if;
|
|
1028
|
|
1029 -- ??? Do we need to yield in case Yielded is False
|
|
1030
|
|
1031 Initialization.Undefer_Abort_Nestable (Self_Id);
|
|
1032 Entry_Call_Successful := Entry_Call.State = Done;
|
|
1033 Entry_Calls.Check_Exception (Self_Id, Entry_Call);
|
|
1034 end Timed_Protected_Entry_Call;
|
|
1035
|
|
1036 ----------------------------
|
|
1037 -- Update_For_Queue_To_PO --
|
|
1038 ----------------------------
|
|
1039
|
|
1040 -- Update the state of an existing entry call, based on
|
|
1041 -- whether the current queuing action is with or without abort.
|
|
1042 -- Call this only while holding the server's lock.
|
|
1043 -- It returns with the server's lock released.
|
|
1044
|
|
1045 New_State : constant array (Boolean, Entry_Call_State)
|
|
1046 of Entry_Call_State :=
|
|
1047 (True =>
|
|
1048 (Never_Abortable => Never_Abortable,
|
|
1049 Not_Yet_Abortable => Now_Abortable,
|
|
1050 Was_Abortable => Now_Abortable,
|
|
1051 Now_Abortable => Now_Abortable,
|
|
1052 Done => Done,
|
|
1053 Cancelled => Cancelled),
|
|
1054 False =>
|
|
1055 (Never_Abortable => Never_Abortable,
|
|
1056 Not_Yet_Abortable => Not_Yet_Abortable,
|
|
1057 Was_Abortable => Was_Abortable,
|
|
1058 Now_Abortable => Now_Abortable,
|
|
1059 Done => Done,
|
|
1060 Cancelled => Cancelled)
|
|
1061 );
|
|
1062
|
|
1063 procedure Update_For_Queue_To_PO
|
|
1064 (Entry_Call : Entry_Call_Link;
|
|
1065 With_Abort : Boolean)
|
|
1066 is
|
|
1067 Old : constant Entry_Call_State := Entry_Call.State;
|
|
1068
|
|
1069 begin
|
|
1070 pragma Assert (Old < Done);
|
|
1071
|
|
1072 Entry_Call.State := New_State (With_Abort, Entry_Call.State);
|
|
1073
|
|
1074 if Entry_Call.Mode = Asynchronous_Call then
|
|
1075 if Old < Was_Abortable and then
|
|
1076 Entry_Call.State = Now_Abortable
|
|
1077 then
|
|
1078 if Single_Lock then
|
|
1079 STPO.Lock_RTS;
|
|
1080 end if;
|
|
1081
|
|
1082 STPO.Write_Lock (Entry_Call.Self);
|
|
1083
|
|
1084 if Entry_Call.Self.Common.State = Async_Select_Sleep then
|
|
1085 STPO.Wakeup (Entry_Call.Self, Async_Select_Sleep);
|
|
1086 end if;
|
|
1087
|
|
1088 STPO.Unlock (Entry_Call.Self);
|
|
1089
|
|
1090 if Single_Lock then
|
|
1091 STPO.Unlock_RTS;
|
|
1092 end if;
|
|
1093
|
|
1094 end if;
|
|
1095
|
|
1096 elsif Entry_Call.Mode = Conditional_Call then
|
|
1097 pragma Assert (Entry_Call.State < Was_Abortable);
|
|
1098 null;
|
|
1099 end if;
|
|
1100 end Update_For_Queue_To_PO;
|
|
1101
|
|
1102 end System.Tasking.Protected_Objects.Operations;
|